Injecting epinephrine into the lower rather than upper thigh may be more effective in obese individuals, according to a study presented at the AAAAI’s 2013 annual meeting.

Epinephrine works best when injected directly into muscle, as opposed to fat, as it absorbs into the bloodstream faster this way. Using ultrasound results, researchers from the U.K. measured the distance between the surface of the thigh and the inner muscle of 93 children. It was discovered that this distance was greater than the length of the auto-injector’s needle in 82 percent of the obese children studied.

At three-quarters down the thigh, the distance was reduced so that only 17 percent still had their muscle out of reach. This suggests that the lower thigh could be a more effective location for giving an epinephrine shot to any obese individual.

Heights, weights, waistline measurements and body mass index data were gathered in order to determine which children would be considered obese.